Up to half of military veterans with traumatic brain injury (TBI) also suffer from co-occurring posttraumatic stress disorder (PTSD). Both are linked to higher risk of chronic pain, one of the most common health complaints among U.S. veterans who served in Operation Enduring Freedom (Afghanistan), Operation Iraqi Freedom (Iraq), and Operation New Dawn (OEF/OIF/OND). However, pain medications elevate risk of opioid abuse, and studies indicate that veterans perceive barriers to traditional mental health treatments. Littl research exists regarding non-pharmacological, technology-based interventions designed to reduce pain in veterans with PTSD and TBI. Mobile technology used to implement neurofeedback (EEG biofeedback) shows promise in providing a portable, low-cost intervention for reducing pain in veterans with co-occurring disorders. In the current R34, we aim to test the feasibility and effectiveness of using mobile neurofeedback devices for reducing pain symptoms in veterans with PTSD and TBI. N=100 OED/OIF/OND veterans with PTSD, TBI, and chronic pain will receive a NeuroSky headset (which reads EEG brain waves) and an iPod Touch with an app called Cortex EEG (which provides neurofeedback to induce physiological relaxation). NeuroSky and Cortex EEG are linked via Bluetooth, and veterans are taught how to use these together to do neurofeedback. With staff assistance, veterans will also enter a schedule and reminders into the iPod calendar to practice neurofeedback by themselves at home or other preferred setting 20 minutes a day, 4 times a week, for 12 weeks. Comprehensive data will be collected before and after the intervention. In the intervening period, we will collect data on app utilization twice by phone and conduct a home visit to practice neurofeedback, troubleshoot technical problems, and collect data on utilization. Guided by existing research and preliminary data, we hypothesize that 80% of participants will show high levels of adherence (25 or more sessions of neurofeedback) to the NeuroSky + Cortex EEG intervention for the 3-month study duration and that participants will show statistically significant reduction in pain symptoms at 3 months compared to baseline. Given links between pain and other outcomes in veterans, we will also explore effects on drug abuse, violence, and suicidality. When the research is complete, the field will be changed because we will know whether new technology reading EEG brainwaves can be used to treat symptoms among individuals suffering from chronic pain. We will also know whether neurofeedback shows promise as an effective intervention for veterans with PTSD and TBI to reduce pain and related outcomes. If these benchmarks are achieved, the R34 will lay the groundwork for a future, large scale randomized clinical trial employing objective neuroimaging and physiological measures to pinpoint mechanisms underlying reduced pain from the intervention and to determine whether improvement persists long term. If this program of research is successful, its impact will be to shift approaches to managing pain in clinical practice, for both veterans and civilians.